The traditional method used to protect roofs or other surfaces from rain and other forms of inclement weather was to lay down several layers of material, normally felt soaked material with bitumen, thereby building up a waterproof membrane. This method has several problems. The first problem is that the process is very long, and is also susceptible to contamination by rainwater or other foreign materials. Secondly, the bitumen must be heated to the point where it gives off noxious odors.
In recent years, alternate systems using elastomeric membranes have become increasingly popular. In these methods, a suitable elastomeric membrane is laid over the top surface of the roof itself or, more preferably, an insulation board. A variety of methods for fastening the elastomeric membrane to the surface of the roof have been developed. One method is to spread an adhesive over the entire surface of the roof before laying down the membrane. This process is very labor-intensive and requires the installers to be exposed to adhesives that give off noxious fumes.
Alternatively, the membrane can be fastened to the roof mechanically. Several devices have been developed which require that a nail or screw be allowed to penetrate the membrane. This can lead to rips and tears in the membrane, especially as the membrane expands and contracts in response to changes in the ambient temperature. These breaches in the integrity of the membrane, in turn, can lead to water leakage and eventual damage to the underlying roof.
Other methods, patented by the applicant herein (U.S. Pat. Nos. 4,858,412 and 4,949,523), disclose a system of attaching the membrane to a roof without penetrating the membrane with a nail or screw or using adhesives that give off noxious fumes.
This invention represents an improvement over both of the above-cited patents, particularly with respect to occasionally observed variations in the equalization of the membrane shrinkage, membrane bunching and/or improper stretching encountered with the prior systems. The features of the present invention, such as but not limited to, the gripper ridges and tapered lips, will help eliminate prior disadvantages like these.